Report: 80 percent of App Store apps aren't visible

Mobile analytics company adjust uses the term "zombie apps" to describe those that aren't visible on the App Store – to be visible, an app must "rank on any of the 39,171 App Store top lists on two out of three days over the month." That's a fairly low bar, but still, last month just one-fifth of apps were visible. The number of zombie apps is climbing – in June 2013, the zombie rate was 70.4 percent, but that rose to 75.2 percent in December, and in June 2014, it reached 79.6 percent (953,387 apps out of 1,197,087), adjust says.

Games are the largest category in the App Store, with 237,389 apps added in the past year, and 65,643 (21.7 percent) of those were removed voluntarily by developers or because they violated Apple's rules. In 2013, the App Store saw 453,902 new apps, and almost 15 percent of those were pulled. Books had the highest rate of pulled apps, at 27 percent, the company reports.

Adjust predicts the App Store will receive 578,000 new apps by July 1, 2015. More than 1.6 million apps have been uploaded to the App Store since its launch, and 350,000 (21.8 percent) have been pulled, adjust says.